Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1054017
INTRODUCTION
This invention relates to a new and improved method for
thickening clays through the use of a water-in-oil emulsion of a
finely divided acrylami~e polymer. This is accomplished by adding
the water-in-oiL emulsion o~ the acrylamide polymer directly to a
clay powder with agitation. The oil phase of the water-in-oil
emulsion serves as a carrier, causing the polymer particles to be
uniformly dispersed throughout the clay. This clay-polymer slurry,
depending on the concentration of the polymer within the slurry, can
be either mixed with more clay or used as is. ~he clay-polymer
slurry is then added to water where the polymer emulsion contained
in the clay inverts, causing the polymer to solublize, giving a
rapid .increase of the viscosity of the clay-polymer-water slurry to
produce a thickened clay.
-The use of water-soluble acrylamide polymers as thickening
agents, is well-known in the art. Commercially, these polymers are
available in two forms: as a dilute liquid: and as a solid.
The dllute liquid acrylamide polymer solutions, have two
disadvantages. one, due to the viscosity of the high molecular
weight material in water, they must be shipped as extremely dilute
solutions, usually within the range of 0.5 to 3% polymer solids. ;
Also, because they are so dilute, they cannot be used l`n~application
where a more concentrated solution is desired. The solid
acrylamide polymers are most often available commercially as
powders or as finely divided solids. DUe to their large particle
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Isize~ a lO0 mesh particle, being on the order of a 150 microns9 it
lis difficult to dispexse these polymers uniformily in clay solutions
: ¦ In order to assure uniform distxibution, they must be dissolved in
¦water. Although the various polymers used are soluble in water,
di~ficulty is often exper:ienced in preparing aqueous polymer
solutions because of slow dissolution, and because the solid
polymer i5 not readily dispersable in water. Furthermoreg dispersior
of solid polymers in water is hindered by their tendency to clump
¦or remain as agglomerates on contact with water. Lumps of solid
¦polymer immediately form by the agglomerating. Although many of the ¦~
` ¦lumps ara eventually dissolved by continued agitation, it is
¦frequently impractical to agitate the solution for a sufficiently
¦long period of time to obtain complete dissolution.
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The method of this invention involves an improved method
for thickening clays through the use of water-in-oil emulsions of ;~
a finely divided acryIamide polymer. The method of this invention
involves adding a water-in-oil emulsion of a fiAely divided
acrylamide polymer to a clay powder followed by agitation to evenly
disperse the emulsion in the clay. The slurry so formed may be
added to water whereupon the polymer inverts or may be added to more
clay powder which is in turn added to water. The metho~ ~of this
invention provides to the art a new and improved method for a
preparing thickened clay solutions in a short period of time, as
well as providiny a clay-polymer dispersion which can be inverted
into water to produce a thickened clay.
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Thus ~his invention seeks to provide a process for the thickening
of clays which compris~s the steps of:
A. adding from 1.0 to 40% by weight of a water-in~oil emulsion :
of a finely divided acrylamide polymer to a clay powder, said water-in-oil
emulsion containing 15 to 40% by weig}lt of an acrylamide polymer;
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B. agitating the mixture to produce a homogeneous concentrated :
slurry o.f the clay and polymer;
C. adding a quantity of the slurry of Step ~ to a volume of ~ ;
water to produce a slurry containing from 0.1 to 10% by weight pol~ner; :
. D. inverting the water-in-oil emulsion of a finely divided ~ ;~
acrylamide polymer contained in the slurry of Step C to produce a thickened
: clay.
As a preferred embodiment this invention seeks to provide a ~ ;
process for the thickening of clays which comprises the steps of:
A. adding to the clay powder from 1 to 40% by weight of a water-
: in-oil emulsion of a finely divided acrylamide polymer, said emulsion con-
`~ taining 15 to 40% by weight of an acrylamide polymer;
; B. agitating the mixture to produce a homogeneous concentrated .
slurry of the clay; ~ .
C. adding the concentrated slurry of Step B to a quantity of :~-
clay powder with agitation so as to produce a clay rich slurry;
D. adding to the clay rich slurry of Step C a quanti~y of water
so that the total polymer concentration is reduced to between 0.1 to 10% by
::1 weight; and then~
E. inverting the water-in-oil emulsion of a finely divided
:~ acrylamide polymer contained in the clay slurry to produce a thickened clay.
~ The polymers most commonly used in the application of this
`~ in~ention are acrylamide polymers which include polyacrylamide and its
water-soluble nonionic, cationic or anionic copolymeric derivatives such as,
~ for instance, acrylic acid, methacrylic acid, itaconic acid, dimethyl-
aminoethylmethacrylate, acrylonitrile and styrene
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land styrene. The copolymers contain from about 5 to 95% by weight
¦f acrylamide. l~he molecular weights of such polymers exceed ,
500,000.
A polymer also useul in the practice of this invention
:is hydrolyzed polyacrylamide which has from 1 to 50% of the original
carboxami.de groups hydrolyzed to carboxyl groups.
l~e molecular weight of the polymers described above may
vary over a wide range, e.g., 10,000 to 25 million. The preferred
polymer has a molecular weight'in excess, of 1 million. `
In'general, the polymer emulsions axe stable yet at the
same time contain relatively large amounts,of pol~mer. The polymers
dispersed in the emulsion are quite stable when the particle si~e
of the polymer is within the range of 2 millimicrons up to about
5 microns. The preferred particle size is within the range of
, 5 millimicrons and 3 microns.
It is extremely important for the purposes of our
invention that particle size is kept as small as,posslble. This
is due to the fact that the small particles are more easily blended
in a uniform fashion than large particles.
The stable water-in-oil emulsion comprises:
~' ' 1. An aqueous phase; '
2. A hydrophobic liquid, and
3. A water-in-oil emulsifying agent. _,~
; The polymer-containing emulsion of this invention is
comprised of an aqueous phase ranging between 30 and 95% by weight
~, of the emulsion. The aqueous phase is defined as the sum of the
polymer or copolymer and the water present in the composition. The ~-
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preferred range is between70 and 90% by wei~ht of th~ emulsion.
The most preferred range is betweell 7~ and 80~ by weig]lt of the
emulsion.
¦ The prcsent invelltion has a polymer concentration between
10 and 50% by weight of the emulsion. A preforred range is between
25 and ~0% by weight of the emulsion. The most preferred range
is between25 and 35% by weight of the emulsion.
The organic or oil phase of the emulsion is comprised
of an inert hydrophobic liquid The hydrophobic liquid usually
comprises between 5 and 7~/oby weight of the emulsion. The preferrec
range is between 5 and 30% by weight of the emulsion. The most
preferred range is between 20 and 30% by weight of the emulsion.
The oils used in preparing these emulsions may be
~elected from a large group of organic liquids which include liquid
hydrocarbons and substituted liquid hydrocarbons. Prefarred
~` groups of organic liquids are hydrocarbon liquids whic~ include
blends of aromatic and aliphatic hydrocarbon compounds, which contair
contain from 4 to 8 carbon atoms. Thus, such organic hydrocarbon
liqulds as benzene, xylene, toluene, mineral oils kerosenes, ~ ;
naphtha, and in certain instances, petroleums may be used. A
particularly useful oil from the standpolnt of its physical and
chemical properties is the branch-chain isoparafinnic solvent sold
by Humble Oil and ~efinery Company under the tradename~iXsopar M~o .
Typical specifications of this narrow-cut isoparaffinic solvent
are set forth below in Table I.
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TABLE I
Specificati.on
ProPerties Minim~ Maximum Test Method
Gravity,
API at 60/60F 48.0 51.0 ASTM D 287
Color, Saybolt 30 - ASq~ D 156
Aniline point, F 185 - ASTM D 611
Sulur~ ppm - 10 ASqM D 1266
(~ephelometric mod.)
Distillation, F
IBP 400 410
Dry point - 495
Flash point, F
(Pensky-Martens
closed cup) 160 -. ASTM D 93
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Any conventional water-in-oil emulsif7ing agent can be used such
as sorbitan monostearate, sorbitan monooleate, and the so-called low HLB
materials which are all documented in the literature and are summarized in
the ~tlas ~ILB Surfactant Selector. ~lthough the mentioned emulsifiers are
usad Ln producing good water-in-oil emulsions, other surfactants may be
used as long as they are c~pable of producing these emulsions. The water-
in~oil emulsifying agent is usually present :in amounts ranging between 0.1
and 5.0% by weight of the emulsion. The preferred range is between 1.0 and
3.o% by weight of the emulsion. The most preferred range is between 1.2
and 2.0% by weight of the emulsion.
The polymers contemplated for use~in this invention may be
synthesized in emulsion form as described in Vanderhoff et al, United States
3,284,393. The polymerization technique set forth in Vanderhoff is
generally followed in preparing polymeric latexes used in this invention.
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Also contemplated in the practice of this invention is the
-~ preparation of suitable water-in-oil emulsions of water-soluble polymers by
the methods described in Anderson et al, United States 3,624,019 and
3,734,873.
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- ~ The water-in-oil emulsion used in the practice of this invention
exhibits the unique ability of rapidly dissolving into aqueous solution.
The polymer-containing emulsion, releases the polymer into water in the
presence of a surfactant, electrolite, or upon physical manipulation such
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as high shear mixing, in a very short period of time. This inversion
technique is described in Anderson et al, United States 3,624,019 and ~ ~
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TIIE METHOD
Once the water-in-oil emulsion of a ~inely divided acryl-
amide polymer is prepared, it is added to a clay powder. The sub-
stance used as the clay may include clays, humates, soils, lignosul-
onates, and minerals, Preferably the water~in-oll emulsion of the
pOlylller i5 added to the clay in a weight percent from 1 to 40/~
based on the dry clay powder. This mixture is ~hen agitated ~o
produce a homogeneous concentrated slurry of the clay. ~t low
polymer levels, the clay totally absorbs the hydrophobic li~uid
phase from the water~in-oil emulsion of the finely divided vinyl
addition polymer. Usually this treated clay still has the appear-
ance of a dry powder. It is only when the clay is contacted with
water that the instant thickening properties appear.
- The oil used in preparing the water-in-oil emulsion servec
as a carrier or the polymer and provides for much easier dispersior
~hat will be possible using a dry pol~ner of equivalent particle
size, After this concentrated slurry of the clay-polymer is formed,
it may be added directly to water to produce a thickened clay with
the polymer concentration being rom 0.1 to 10% by weight of th~
aqueous solution, In the preferred embodiment of our invention the
concentrated clay-p~lymer slurry is added to an additional quantity
of clay power, with agitation9 so as to produce a clay-rich slurry
which upon addition of water will produce a thickened clay o the
desired polymer concen~ration without excessive dilution, When
water in the presence of a hydrophilic surfactant is added to the
clay-polymer slurry, the polymer within the emulsion inverts, caus-
ing an almost ins~antaneous thickening effect, Typically, in the
final thickened clay slurry the pol~ner concentration should be in
the range of 0.1 ~o 10% with the clay cDmprisin~ a substantial
portion of the mixture.
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The polymer contained within the clay-rich slurry
may be inverted by the use of a surfactant. The surfactant so
employed may be added to the aqueous solution into which the
clay-polymer slurry wil:L be added, or to the water_in-oil
cmuLsion of a Einely di~ided acrylamide polymer, beEore its
addition to the cLay to render it self-inverting upon contact
with water.
The surfactant may be present in amounts ranging
from .01 to 50% by weight based on the polymer contained in the
0 water-in-oil emulsion. However, generally the surfactant
concentration is within the range 1.0 to 10% by weight based
on polymer.
` The preferred surfactants are hydropholic and are
1` further characteri~ed as being water-soluble. Any hydrophilic-
type surfactant surh as etho~lated nonyl phenols, ethoxylated
nonyl phenol formaldehyde resins, dioctyl esters of sodium
sulfosuccinate, and octyl phenol polyethoxyethanol can be
used~ Basically, any anionic, cationic or nonionic surfactant
can be employed in this invention. The surfactants are fully
o disclosed in U.S. 3j624,019.
The surfactants chosen, however, should be tried on
a case-by-case basis due to variances in the water-in-oil
emulsions, the salt content, and pH of the inorganic nitrate
- salt slurries~ and the water-in-oil emulsifier used originally~The method of this invention thus allows for the
rapid preparation of thickened clays, which may be done
using the clay and a water_in-oil emulsion~,of a finely
divided acrylamide polymer, or in the field, using a clay-rich
slurry.
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The amount of pol~ner, clay, and water used, will depend on the
; desired viscosity of the thickened clay. The use of more water will cause
a decrease in viscosity. The use of greater amounts of polymer and greater
amounts of clay will cause an increase in the viscosity. The following
c~amples are offercd to illustrate our invention.
EXAMPLk'Z 1
ISOPAR ~Z 27.6 grams
Sorbitan Monostearate 1.65 grams
Water 40.20 grams
Acrylamide 36.51 grams
SZodium Hydroxide 2.29 grams
2,2'azobis (isobutyronitrile)0.0~ grams
The sorbitan monostearate was dissolved in the ISOPAR M* and the ~ ;
resulting solution was poured into a two liter glass reactor fitted with a
~10 stirrer, thermometer, and nitrogen purge. The monomer solution was prepared
by dissolving the acrylamide in water. The pH of the monomer solution was
adjusted to 8.5 with sodiuZm hydroxide. The monomer solution was added to
the organic phase with rapid agitation. The reactor was purged for 30
minutes after which time the 2Zl2~azobis (isobutyronitrile) dissolved in
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acetone was added to the mixture. The emulsion was heated to 60C with
agitation. The reaction proceeded for 2-1/2 hours at which time it had
reached completion. The resulting product was a stable emulsion.
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¦ EX~MPLE 2
Acrylamide-acrylic acid emulslon reci~e:
ISOPAR M 28.10 grams
Sorbitan Monostearate 1.85 grams
Water 40.00 grams
Acrylamide 33.90 grams
Acry]ic Acid 2.40 grams
Sodium Hydroxide 2.30 grams
2,2'a~obis (isobutyronitrile) 0.07 grams
As in ~xample 1, the sorbitan monostearate was dissolved
in the ISOPAR M and the resulting solution was poured into a two
liter glass reactor fitted with a stirrer, thermometer, and
nitrogen purge. The monomer solution was prepared by dissolving
the acrylamide and acrylic acid in watex. The pH of the monomer
solution was adjusted to 8.5 with sodium hydroxide. Th~ monomer
solution was added to the organic phase with rapid agitation. The
reactor was purged for 30 minutes after which time the 2,2'azobis
(isobutyronitrile) dissolved in acetone was added to the mixture.
The emulsion was heated to 60C with agitation. The reaction pro~
ceeded for 2-1/2 hours at which time it had reached completion.
The re ul~ing product was a stable emu1sion:
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I EX~MPL~ 3
¦Acrylaml~e-mcth~cr~lic acid emulsio~ recipe:
¦ ISOPAR M 27.6 grams
¦ Sorbitan Monostearate1;65 grams
Water 40.20 grams
¦ Acrylamide 34.51 grams
¦ Meth~crylic Acid2.31 grams
¦ Sodium Hydroxide2.29 grams
l 2,2'azobis (isobutyronitrile) 0.07 grams '
¦ me sorbitan monostearate was dissolved in the ISOPAR M
~nd the xesulting solution was poured into a two liter glass
¦ eactor fitted with a stirrer, thermometer, and nitrogen purge. The
¦ onomer solution was prepared by dissolving the acrylamide and
methacrylic acid in water. The pH of the monomer solution was
adjusted to 8.5 with sodium hydroxide. The monomer solution was
added to the organic phase with rapid agitation. The reactor was
purged or 30 minutes a~ter which time the 2,2'azobis ~ ~-
(isobutyronitrile) dissolved in acetone was added to the mixture.
The emulsion was heated to 60C with agitation. The reaction pro-
ceeded for 2-1/2 hours at which time it had reached completion.
~he resulting produce was a stable emulsion.
This invention is further illustrated by the ollowing
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EXA~IPL~ 4
The water-in-oil emulsion of a finely divided acrylamide polymer
oE Example 2, was added to Wyoming sodium bentonite at a S% level (1.7%
polymer solids). A 1% solution of the sodium bentonite, in water, containing
.17% nonylphenol which had been reacted with 10 moles oE ethylene oxide,
increased the viscosity from 50 to 100 cps as a result of this polymer
addition. In practice, the 5% slurry of the emulsion in sodium bentonite
could be added to more sodium bentonite to achieve any intermediate viscosity.
EXAMPLE 5
The water-in-oil emulsion of a finely divided acrylamide polymer
of Example 1, was added to a Wyoming sodium bentonite at 5% level (1.68%
pol~ner solids). A 1% solution of this sodium bentonite in water containing
0.15% nonylphenol which had been reacted with 10 moles of eth~lene oxide,
increased the viscosit~ from about 50 to about 100 cps as a result of this
E polymer addition.
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